1640s, "course, direction," from Latin ductus "a leading, a conduit pipe," noun use of past participle of ducere "to lead" (from PIE root *deuk- "to lead"). Anatomical sense "vessel of an animal body by which blood, lymph, etc., are conveyed" is from 1660s. Meaning "conduit, channel" is 1713; that of "air tube in a structure" is from 1884.
Duct tape originally was duck tape (1894), long, non-adhesive strips of plain cotton duck cloth used in various mechanical processes; from duck (n.2). The name was transferred to a plastic-coated adhesive tape used by U.S. soldiers in World War II (perhaps in part because it was waterproof). It continued in civilian use after the war, and the name shifted to duct tape by 1958, perhaps because it was frequently used on air ducts, which also accounts for its standard silver-gray color.
1931, from the theories, experiments, and methods of Russian physiologist Ivan Petrovich Pavlov (1849-1936), especially in connection with the conditioned salivary reflexes of dogs in response to the mental stimulus of the sound of a bell (attested from 1911, in Pavloff [sic] method).
type of contagious disease characterized by inflammation of the glands, c. 1600, from plural of mump "a grimace" (1590s), originally a verb, "to whine or mutter like a beggar" (1580s), from Dutch mompen "to cheat, deceive," originally probably "to mumble, whine" and of imitative origin (compare mum (interj.), mumble). The infectious disease probably was so called in reference to swelling of the salivary glands of the face and/or to painful difficulty swallowing. Mumps also was used from 17c. to mean "a fit of melancholy, sullenness, silent displeasure."
An extensive bridge consisting, strictly of a series of arches of masonry, erected for the purpose of conducting a road or a railway a valley or a district of low level, or over existing channels of communication, where an embankment would be impracticable or inexpedient; more widely, any elevated roadway which artificial constructions of timber, iron, bricks, or stonework are established. [Century Dictionary]
But the word apparently was coined by English landscape gardener Humphry Repton (1752-1818) for an architectural feature, "a form of bridge adapted to the purposes of passing over, which may unite strength with grace, or use with beauty ...."
Old English pipe "simple tubular musical wind instrument," also "tube for conveying water," from Vulgar Latin *pipa "a pipe, tube-shaped musical instrument" (source also of Italian pipa, French pipe, Old Frisian pipe, German Pfeife, Danish pibe, Swedish pipa, Dutch pijp), a back-formation from Latin pipare "to chirp or peep," of imitative origin.
All the tubular senses ultimately derive from the meaning "small reed, whistle." From late 14c. as "a tube or duct of the body." From mid-15c. as "one of the tubes from which the tones of an organ are produced." Meaning "narrow tubular device for smoking" is recorded by 1590s. As "the sound of the voice," 1570s.
Pipe-bomb, "home-made bomb contained in a metal pipe," is attested from 1960. Pipe-cleaner, "piece of wire coated with tufted material," is recorded from 1863. Pipe-clay "white clay suitable for making smoking pipes" is attested by 1777.
It forms all or part of: abduce; abducent; abduct; abduction; adduce; aqueduct; circumduction; conduce; conducive; conduct; conductor; conduit; deduce; deduction; dock (n.1) "ship's berth;" doge; douche; ducal; ducat; Duce; duchess; duchy; duct; ductile; duke (n.); educate; education; induce; induction; introduce; introduction; misconduct; produce; production; reduce; reduction; seduce; seduction; subduce; subduction; taut; team (n.); teem (v.1) "abound, swarm, be prolific;" tie (n.); tow (v.); traduce; transducer; tug; zugzwang.
It is the hypothetical source of/evidence for its existence is provided by: Latin dux (genitive ducis) "leader, commander," in Late Latin "governor of a province," ducere "to lead;" Old English togian "to pull, drag," teonteon "to pull, drag;" German Zaum "bridle," ziehen "to draw, pull, drag;" Middle Welsh dygaf "I draw."